Navigation

    CFD中文网

    CFD中文网

    • Login
    • Search
    • 最新

    大涡模拟壁湍流雷诺剪切应力

    OpenFOAM
    3
    6
    1640
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • E
      ewz last edited by

      最近验证算例,LES模拟壁面湍流,与文献结果对比,雷诺应力偏离较大;
      采用边界层网格,第一层网格尺寸满足y+=1,入口出口cyclicAMI周期边界条件,因为是不可压缩,所以fvoption直接给出的是Ubar,大概算了80个周期后,做时均,平均速度与文献结果差不多,但关于速度脉动的湍动能和雷诺应力完全不一致,这个问题一直也没有解决,求教高手解答;
      注:关于雷诺剪切应力我是通过uprime2mean_xy+turbulencefieldsR_xy得到的,模拟输出的turbulencefieldsR相比uprime2mean来说很小;

      1 Reply Last reply Reply Quote
      • 李东岳
        李东岳 管理员 last edited by

        1. 可以出个图看看差别有多大

        2. LES那面Van Driest dampling用的比较多,从文献来看可以大大改善壁面附近的预测

        CFD课程 改成线上了 http://dyfluid.com/class.html
        CFD高性能服务器 http://dyfluid.com/servers.html

        E 1 Reply Last reply Reply Quote
        • E
          ewz @李东岳 last edited by

          @东岳 老师,目前在试算,所以我用的是一套二维网格,亚格子模型为WALE

          simulationType LES;
          
          LES
          {
              LESModel        WALE;
          
              turbulence      on;
          
              printCoeffs     on;
          
              delta           cubeRootVol ;
          
              cubeRootVolCoeffs
              {
                  deltaCoeff      1;
              }
          
              PrandtlCoeffs
              {
                  delta           cubeRootVol;
                  cubeRootVolCoeffs
                  {
                      deltaCoeff      1;
                  }
          
                  smoothCoeffs
                  {
                      delta           cubeRootVol;
                      cubeRootVolCoeffs
                      {
                          deltaCoeff      1;
                      }
          
                      maxDeltaRatio   1.1;
                  }
          
                  Cdelta          0.158;
              }
          
              vanDriestCoeffs
              {
                  delta           cubeRootVol;
                  cubeRootVolCoeffs
                  {
                      deltaCoeff      1;
                  }
          
                  smoothCoeffs
                  {
                      delta           cubeRootVol;
                      cubeRootVolCoeffs
                      {
                          deltaCoeff      1;
                      }
          
                      maxDeltaRatio   1.1;
                  }
          
                  Aplus           26;
                  Cdelta          0.158;
              }
          
              smoothCoeffs
              {
                  delta           cubeRootVol;
                  cubeRootVolCoeffs
                  {
                      deltaCoeff      1;
                  }
          
                  maxDeltaRatio   1.1;
              }
          }
          

          您说的van driest damping是vanDriestCoeffs里的设置吗?
          1562635936(1).jpg
          上面的图是平均速度,实验数据为黑线,下方的正弦曲线是底部边界;5-30s我开始认为湍流没有完全发展,所以一直算到200s,又对100-200s取时均,定性上看,两个时间段的平均速度变化差不多;
          雷诺应力的图被我删掉了,有关于湍动能的结果,实验数据为黑线,这个就完全不一致,而且不同时间段的湍动能时均值也不一致;
          1562635976(1).jpg
          以下是我的设置:

          FoamFile
          {
              version     2.0;
              format      ascii;
              class       volScalarField;
              object      nut;
          }
          // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
          
          dimensions      [0 2 -1 0 0 0 0];
          
          internalField   uniform 0;
          
          boundaryField
          {
              INLET
              {
                  type            cyclicAMI;
              }
          
              OUTLET
              {
                  type            cyclicAMI;
              }
          
              BOTTOMWALL
              {
                  type            nutUSpaldingWallFunction;
                  value           uniform 0;
              }
          
              ATMOSPHERE
              {
                  type            nutUSpaldingWallFunction;
                  value           uniform 0;
                
              }
              
              frontAndBackPlanes
              {
                  type            empty;
              }
          
             
          }
          
          FoamFile
          {
              version     2.0;
              format      ascii;
              class       volScalarField;
              object      p;
          }
          // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
          
          dimensions      [0 2 -2 0 0 0 0];
          
          internalField   uniform 0;
          
          boundaryField
          {
              INLET
              {
                  type            cyclicAMI;
              }
          
              OUTLET
              {
                  type            cyclicAMI;
              }
          
              BOTTOMWALL
              {
                  type            zeroGradient;
              }
          
              ATMOSPHERE
              {
                  type            zeroGradient;
                  //p0              uniform 0;
              }
              
              frontAndBackPlanes
              {
                  type            empty;
              }
          
           
          }
          
          FoamFile
          {
              version     2.0;
              format      ascii;
              class       volVectorField;
              object      U;
          }
          // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
          
          dimensions      [0 1 -1 0 0 0 0];
          
          internalField   uniform (0 0 0);
          
          boundaryField
          {
              INLET
              {
                  type                cyclicAMI;
              }
          
              OUTLET
              {
                  type                cyclicAMI;
              }
          
              ATMOSPHERE
              {
                  type                noSlip;
                  //value               uniform (0 0 0);
              }
          
              BOTTOMWALL
              {
                  type                noSlip;
                  
              }
          
              frontAndBackPlanes
              {
                  type            empty;
              }
          }
          
          FoamFile
          {
              version     2.0;
              format      ascii;
              class       dictionary;
              location    "constant";
              object      fvOptions;
          }
          // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
          
          momentumSource
          {
              type            meanVelocityForce;
          
              selectionMode   all;
          
              fields          (U);
              Ubar            (0.08 0 0);
          }
          
          FoamFile
          {
              version     2.0;
              format      ascii;
              class       dictionary;
              location    "system";
              object      fvSchemes;
          }
          // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
          
          ddtSchemes
          {
              default         Euler;
          }
          
          gradSchemes
          {
              default         Gauss linear;
          }
          
          divSchemes
          {
              default         none;
              div(phi,U)      bounded Gauss linearUpwind grad(U);
              div(phi,k)      bounded Gauss limitedLinear 1;
              div(phi,epsilon) bounded Gauss limitedLinear 1;
              div(phi,omega)  bounded Gauss limitedLinear 1;
              div(phi,v2)     bounded Gauss limitedLinear 1;
              div((nuEff*dev2(T(grad(U))))) Gauss linear;
              div(nonlinearStress) Gauss linear;
          }
          
          laplacianSchemes
          {
              default         Gauss linear corrected;
          }
          
          interpolationSchemes
          {
              default         linear;
          }
          
          snGradSchemes
          {
              default         corrected;
          }
          
          wallDist
          {
              method meshWave;
          }
          
          FoamFile
          {
              version     2.0;
              format      ascii;
              class       dictionary;
              location    "system";
              object      fvSolution;
          }
          // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
          
          solvers
          {
              p
              {
                  solver          PCG;
                  preconditioner  DIC;
                  tolerance       1e-06
                  relTol          0.05;
              }
          
              pFinal
              {
                  $p;
                  relTol          0;
              };
          
              "(U|k|B|nuTilda)"
              {
                  solver          smoothSolver;
                  smoother        GaussSeidel;
                  tolerance       1e-05;
                  relTol          0;
              }
          }
          
          PISO
          {
              nCorrectors     2;
              nNonOrthogonalCorrectors 0;
              pRefCell        0;
              pRefValue       0;
          }
          

          希望得到老师的回复,谢谢。

          1 Reply Last reply Reply Quote
          • 李东岳
            李东岳 管理员 last edited by 李东岳

            @ewz 把你的divSchemes里面的bounded去掉,然后时间精度换backward试试。还有就是nut的边界条件nutUSpaldingWallFunction,这个可以换别的试试,具体哪个更好也说不清。

            另外,你模拟的是什么?挺有意思的,要发SCI么,可以考虑下 http://www.cfd-china.com/topic/1716/cfd验证算例支持计划

            黑线是实验数据,红线是什么?

            vanDriest这样用:

            simulationType LES;
            
            LES
            {
                LESModel        WALE;
            
                turbulence      on;
            
                printCoeffs     on;
            
                delta           vanDriest;//
            
                cubeRootVolCoeffs
                {
                    deltaCoeff      1;
                }
            
                PrandtlCoeffs
                {
                    delta           cubeRootVol;
                    cubeRootVolCoeffs
                    {
                        deltaCoeff      1;
                    }
            
                    smoothCoeffs
                    {
                        delta           cubeRootVol;
                        cubeRootVolCoeffs
                        {
                            deltaCoeff      1;
                        }
            
                        maxDeltaRatio   1.1;
                    }
            
                    Cdelta          0.158;
                }
            
                vanDriestCoeffs
                {
                    delta           cubeRootVol;
                    cubeRootVolCoeffs
                    {
                        deltaCoeff      1;
                    }
            
                    smoothCoeffs
                    {
                        delta           cubeRootVol;
                        cubeRootVolCoeffs
                        {
                            deltaCoeff      1;
                        }
            
                        maxDeltaRatio   1.1;
                    }
            
                    Aplus           26;
                    Cdelta          0.158;
                }
            
                smoothCoeffs
                {
                    delta           cubeRootVol;
                    cubeRootVolCoeffs
                    {
                        deltaCoeff      1;
                    }
            
                    maxDeltaRatio   1.1;
                }
            }
            

            CFD课程 改成线上了 http://dyfluid.com/class.html
            CFD高性能服务器 http://dyfluid.com/servers.html

            E ustbwenwu 2 Replies Last reply Reply Quote
            • E
              ewz @李东岳 last edited by

              @东岳 好的,谢谢老师!我调试参数再算一下;
              我模拟的是wave surface壁面湍流,因为目前是验证LES的阶段,就找了一篇关于实验的文献;
              红线数据是三维计算域的实验结果;

              1 Reply Last reply Reply Quote
              • ustbwenwu
                ustbwenwu @李东岳 last edited by

                @李东岳 WALE不需要vanDriest吧?

                1 Reply Last reply Reply Quote
                • Referenced by  C coolhhh 
                • First post
                  Last post

                CFD中文网 | 东岳流体 | 京ICP备15017992号-2